Diode and power supply clamps are used as the main workhorse for electrostatic discharge (ESD) protection. However, with drastic scaling of technology and decreasing oxide thickness, make the known methods insufficient; as it produces a relatively high clamping voltage at the I/O pad.
As electronic components become smaller and smaller along with the internal structures in integrated circuits, it is becoming easier to either completely destroy or otherwise impair electronic components. In particular, many integrated circuits are highly susceptible to damage from the discharge of static electricity, even at levels which can neither be seen nor felt. This is typically referred to as electrostatic discharge (ESD), in which the transfer of an electrostatic charge occurs between bodies at different electrostatic potentials (voltages) caused by direct contact or induced by an electrostatic field.
The discharge of static electricity, or ESD, has become a critical problem for the electronics industry. Device failures are not always immediately catastrophic, but often the device is weakened thus less able to withstand normal operating stresses and, hence, may result in a reliability problem. Therefore, various ESD protection circuits must be included in the device to protect the various components, with various considerations necessary for ESD protection circuits.
Much effort has been expended by industry to protect electronic devices from ESD damage. Traditionally, ESD designs are custom designed using graphical systems. ESD ground rules and structures are typically built into the designs requiring a custom layout. This has lead to custom design for digital products such as, for example, DRAMs, SRAMs, microprocessors, ASIC development and foundry technologies.
In order to meet performance targets, advanced CMOS technologies are pushing the limits of device capabilities. However, with aggressive scaling, device reliability is becoming a measure of device performance. As the limits of device capabilities are reached, factors such as device reliability due to ESD sensitivity become more critical, while at the same time difficult to address.